Friday, March 20, 2026

Gakken SX-150 mk II Tuning (Rossum Compensation)

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      Last time we looked into tuning the oscillator of the Gakken . We assumed a perfect exponential response though, to simplify the conce...
Monday, March 16, 2026

Gakken SX-150 mk II & MIDI Autotune fundamentals

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      I'm a big fan of small, toy synths and today we have the decidedly chintzy Gakken SX-150 mark II. It's the follow up to the ...
Sunday, March 1, 2026

Arduino Nano R4 Input Capture (Guitar Tuner)

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     I bought some of the new Arduino Nano R4 boards to play with. These boards step up from AVR to ARM (RA4M1) microcontrollers while still...
Monday, October 27, 2025

Famicom PCB and Schematic Redraw

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    There are several schematics for the Famicom, but they're all a little different. It's not clear if this is from different board...
Saturday, July 19, 2025

Adding MIDI to the Electro Harmonix EH400 Mini Synthesizer

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     Once again we return to the EH400. This time we're looking at adding MIDI.      This mod is for a friend and needs to retain the us...
Saturday, March 15, 2025

A lightweight ADSR for AVRs

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     I've been doing more projects that involve digital control of analog circuits, and I found myself needing to generate ADSR envelope...
Thursday, January 23, 2025

Timex Sinclair 1000 New Case and Keyboard

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     The Timex Sinclair 1000 (ZX81) is a charmingly limited computer from 1982. It has one of the worst keyboards of all time, and it begs f...
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